The present invention is directed to an occupant sensing system and an associated method, and is particularly directed to occupant sensing using an image sensor to sense an occupant.
Occupant protection systems are well known in the art and are employed in vehicles to help protect vehicle occupants during a vehicle crash event. Most occupant protection systems include one or more actuatable components, such as an air bag, a seat belt pretensioner, a side curtain, etc. During a crash event, these components may be actuated to help protect the vehicle occupant.
Deployment or actuation of the actuatable component is usually dependent upon numerous criteria, such as crash conditions and/or occupant characteristics. A crash condition may be indicated by a crash metric, such as crash acceleration, crash velocity, crash displacement, etc. For example, if a crash metric, such as crash acceleration, is greater than a predetermined threshold crash acceleration value, then this may be regarded as an indication that the crash event is a deployment crash event (e.g. a crash event having a magnitude and/or duration great enough to warrant actuation of the actuatable protection component).
Relevant occupant characteristics may include presence, position, and weight of the occupant. With reference to an air bag, for example, deploying the air bag is wasteful if an occupant is not present. Also, depending on the size and position of an occupant that is present, deploying the airbag may not enhance protection of the occupant; thus, it may be desirable to suppress actuation. Alternatively, depending on the size and position of an occupant who is present, it may be desirable to limit the pressure of the inflation fluid in the inflated air bag.
Several different arrangements and methodologies have been developed to sense these occupant characteristics. For example, imaging technologies have been utilized to acquire an image of the interior of a vehicle to determine the presence and/or position of an occupant.
U.S. Pat. No. 6,005,958 shows an occupant type and position detection system that uses an infrared camera to generate image data of the front seating area of a vehicle. The data are used to track occupant type and position relative to a fixed structure such as the vehicle instrument panel, to optimize the controlling of deployment of an occupant safety device, such as an air bag.
U.S. Pat. No. 5,531,472 discloses an image sensor that is used to obtain image data which is representative of an occupant on a vehicle seat. The image data is compared to stored image data to obtain the occupant""s size and position within the vehicle.
U.S. Pat. No. 5,528,698 discloses an image sensor that acquires a representation of the passenger seat area within a vehicle. Objects within the field of view of the sensor are discriminated to determine whether a rear facing child seat is located in the passenger seat.
In some cases, structured lighting (as opposed to diffuse lighting) is used to create a 3D visual image of an object. Structured lighting alone does not, however, provide sufficient coverage to support 2D occupant recognition techniques. In addition, the source of a structured light must be located at a position and perspective that differs sufficiently from that of the camera to allow recognition of the distortions created by overlaying the structured lighting on an object that has 3D structure. This results in the added cost of extended or dual packaging to accommodate the spaced locations of the camera and light source.
In one aspect, the present invention is an apparatus for determining the location of a vehicle occupant in a vehicle interior. The apparatus comprises a light source for projecting at least one structured light beam onto an area of interest in the vehicle interior to form a light pattern on the area of interest. A beam divergence control device alters the apparent location of the light source with respect to the area of interest. An imager detects the light reflected from the area of interest. A characteristic of the reflected light is measured, and the distance between the imager and the area of interest is measured, based on the measured characteristic of the reflected light.